New method to pull MtGox trade data #bitcoin

* These fields represent the app ID when an app is being used to make the trade. Currently, these are null for all but 4% of trades. There are two fields because there are two parties to every trade, one who is buying the BTC (the bidder) and another who is selling it (the asker). For most of these 4% app trades, only one of the parties is an app, however there are also ~3500 trades for which both parties are apps and both of these fields are non-null.